color.go

package consolizer

import (
	"github.com/gdamore/tcell/v2"
	"github.com/supercom32/consolizer/constants"
	"github.com/supercom32/consolizer/internal/math"
)

/*
GetTransitionedColor allows you to obtain a color that has been transitioned
to another color by a specific percent. For example, if your source color is
red (255, 0, 0) and your target color is green (0, 255, 0), transitioning
by 0.5 (fifty percent) will yield the color (128, 128, 0). In addition, the
following information should be noted:

- If your percent change yields color indexes which are not evenly divisible,
then the color index will be rounded up or down to the nearest whole number.
For example: 50% of color index 255 would yield the color index 128.

- If you pass in a percent change of less than 0.0 or greater
than 1.0, you are simply specifying that you want to transition the color
greater than 100%. For example, a value of 1.2 would mean you want to
transition to 120% of the target color, and a value of -0.2 would mean you
want to transition to -20% of the target color.

- If the resultant transitioned color falls outside of the RGB range of
Black (0, 0, 0) or White (255, 255, 255), it will be defaulted to closest
valid color.
*/
func GetTransitionedColor(sourceColor constants.ColorType, targetColor constants.ColorType, percentChange float32) constants.ColorType {
	var sourceColorIndex [3]int32
	var targetColorIndex [3]int32
	var newColorIndex [3]int32
	sourceColorIndex[0], sourceColorIndex[1], sourceColorIndex[2] = GetRGBColorComponents(sourceColor)
	targetColorIndex[0], targetColorIndex[1], targetColorIndex[2] = GetRGBColorComponents(targetColor)
	for currentColorIndex := 0; currentColorIndex < 3; currentColorIndex++ {
		colorDifference := targetColorIndex[currentColorIndex] - sourceColorIndex[currentColorIndex]
		colorDifference = int32(math.RoundToWholeNumber(float32(colorDifference) * percentChange))
		if colorDifference < 0 {
			colorDifference = int32(math.GetAbsoluteValueAsFloat64(colorDifference))
			newColorIndex[currentColorIndex] = sourceColorIndex[currentColorIndex] - colorDifference
		} else {
			newColorIndex[currentColorIndex] = sourceColorIndex[currentColorIndex] + colorDifference
		}
		if newColorIndex[currentColorIndex] > 255 {
			newColorIndex[currentColorIndex] = 255
		}
		if newColorIndex[currentColorIndex] < 0 {
			newColorIndex[currentColorIndex] = 0
		}
	}
	return constants.ColorType(tcell.NewRGBColor(newColorIndex[0], newColorIndex[1], newColorIndex[2]))
}

/*
GetRGBColorComponents allows you to obtain RGB color component indexes for
red, green, an blue color channels.
*/
func GetRGBColorComponents(color constants.ColorType) (int32, int32, int32) {
	var redColorIndex int32
	var greenColorIndex int32
	var blueColorIndex int32
	redColorIndex, greenColorIndex, blueColorIndex = tcell.Color.RGB(tcell.Color(color))
	return redColorIndex, greenColorIndex, blueColorIndex
}